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Ionic liquids (ILs) have many potential applications in the chemical industry. In order to understand ILs, their molecular details have been extensively investigated. Intuitively, electrostatic forces are solely important in ILs. However, experiments and calculations have provided strong evidence for the existence of H-bonds in ILs and their roles in the properties and applications of ILs. As a structure-directing force, H-bonds are responsible for ionic pairing, stacking and self-assembling. Their geometric structure, interaction energy and electronic configuration in the ion-pairs of imidazolium-based ILs and protic ionic liquids (PILs) show a great number of differences compared to conventional H-bonds. In particular, their cooperation with electrostatic, dispersion and π interactions embodies the physical nature of H-bonds in ILs, which anomalously influences their properties, leading to a decrease in their melting points and viscosities and thus fluidizing them. Using ILs as catalysts and solvents, many reactions can be activated by the presence of H-bonds, which reduce the reaction barriers and stabilize the transition states. In the dissolution of lignocellulosic biomass by ILs, H-bonds exhibit a most important role in disrupting the H-bonding network of cellulose and controlling microscopic ordering into domains. In this article, a critical review is presented regarding the structural features of H-bonds in ILs and PILs, the correlation between H-bonds and the properties of ILs, and the roles of H-bonds in typical reactions. [ABSTRACT FROM AUTHOR]

Ammonia is a vital chemical raw material, but it is also a highly toxic environmenal pollutant. However, its highly efficient uptake and reversible release is a challenge. Herein, we have designed and synthesized a series of hybrid materials for efficient NH3 capture by confining calcium chloride (CaCl2) in a porous covalent organic framework (COF). A high capture capacity of 26.5 mmol g−1 is obtained at 25 °C and 1 bar, which is the highest value among existing porous materials, and NH3 can be easily desorbed at 80 °C under vacuum for 2 h. Particularly, the hybrid COF is highly efficient for the absorption of low NH3 content. Such excellent performance is ascribed to the highly dispersion of CaCl2 in the pores of the COF, and coordinating interaction of NH3 to Ca2+ together with hydrogen bond interaction between NH3 and Cl−. [ABSTRACT FROM AUTHOR]

The targeted synthesis of three-dimensional covalent organic frameworks (3D COFs) is a great challenge, especially those synthesized by using a new kind of organic linkage. Herein, for the first time, a novel 3D azine-linked COF (3D-HNU5) has been synthesized and characterized. It is shown that the obtained 3D COF has a 2-fold interpenetrated diamond topology, and shows good chemical/thermal stability and a narrow pore size distribution, which exhibits excellent performance in the selective uptake of CO2 over N2. Moreover, the 3D-HNU5 is found to be an efficient catalyst for the cycloaddition of propargylic alcohols with CO2 into carbonates with excellent catalytic activity under mild conditions. [ABSTRACT FROM AUTHOR]

A hybrid shell material of hollow Nb2O5 microspheres has been engineered as an effective sulfur host for use in Li–S batteries. Of particular note is that the selected Nb2O5 not only exhibits ultrafast Li+ motion properties due to its unique room-and-pillar NbO6/NbO7 framework structure, but also demonstrates moderate polar affinities to the lithium polysulfides based on theoretical calculations. [ABSTRACT FROM AUTHOR]

It is a challenge to develop microemulsions which can serve as nanoreactors for the synthesis of nanoparticles and chemical reactions at high temperature. In this work, a class of novel high temperature microemulsions consisting solely of ionic liquids have been designed and prepared for the first time. It is found that nanoscale droplets formed in the ionic liquid microemulsions can be maintained up to 200 °C, and the size distribution of the droplets can be easily tuned by selection of the ionic liquids and varying compositions of the systems. By using such microemulsions as nanoreactors, porous metals such as Pt have been prepared at 180 °C without using any purposely added reductant. [ABSTRACT FROM AUTHOR]

The charge transfer and active sites of metal-free imidazolium-based composites were unveiled by an electrochemical method with high sensitivity and selectivity due to the specific donor–acceptor coupling of imidazolium with NO2−. [ABSTRACT FROM AUTHOR]

Correction for 'An azobenzene-modified redox-active ionic liquid electrolyte for supercapacitors' by Yuhua Zhao et al., Chem. Commun., 2022, https://doi.org/10.1039/d2cc04081f. [ABSTRACT FROM AUTHOR]